Biogas TechnologySuccessful projects in Asia and Africa Dr David Fulford With help from
What is Anaerobic Digestion (biogas)?Cow isanaerobicdigester: gut has population of organisms: break down food for energyBiogas plant: contains slurry at 35°C,no oxygen, contain slurry, gas tight
Two scales of biogasLarge-scale systemsIndustrial processingTank volume:10,000 m3 andaboveFeed material:500 tonnes aday andupwards
Two scales of biogasSmall-scale systems - AsiaDomestic processingTank volume:1 to 10 m3Feed material:2 to 60 kg aday
Inputs to a biogas plantCattle dungseen as goodfeedstock: correct organisms; food chewed so accessible to organismsOther animal dung: pig, horse, chickenHuman sewage
Inputs to a biogas plantFood processing residues e.g. market wastesVegetable mattergives more gasper kg, than dung(animals & humansalready used energy)Used to cleanwaste waterse.g. from coffee orsugar production.
Inputs to a biogas plantEnergy Crops Grown especially for energy productionWastes can bemixed: e.g. Dung + sewage Food residues + sewageAll can be used atany scale: Domestic to Industrial
Outputs from a biogas plant Biogas: 60% methane 40% carbon dioxide: high grade fuel Used for cooking Replace firewood and charcoal, so reduces deforestation. Replace LPG and kerosene, so saves fossil carbon
Outputs from a biogas plant Biogas: used as an engine fuel Static engines to generate electricity Need large amounts of feed material 1 tonne/day = 1 kW Compress gas - use in vehicles Need 50% energy in gas to do so.
Outputs from a biogas plant Compost - value as an organic fertilizer Can be used as liquid or dried Better to absorb in dry biomass (straw) and then leave to compost
Outputs from a biogas plant Compost –add vermi-compost to get very high value fertilizer Gives 30% greater crop yields Worth £30 a tonne cash-in-hand Reduces pests and diseases
History of biogasMarsh gas used in C10 BC to heat bath water (Assyria) to make salt from sea water (China)First biogas system in India – Leper colony in Mumbai 1859“Monster Septic Tank” gave gas forstreet lights in Exeter 1895.Used in sewage systems in Europefrom 1930s.
History of biogasChina 1920: Rural biogas systems developed 1958: National programme started 1978: 7 million plants built, but only 3 million working Part of Chairman Mao’s “Great Leap Forward” Emphasis on rural self-support, Built by local people But lacking in quality control
History of biogasChina 1979: Chengdu Biogas Centre offers quality control New emphasis on training, follow-up and monitoring Individual family plants, use pig dung, human sewage and food wastes Sanitation + gas + compost2009: About 17 million biogas plants (< 50% success)
History of biogasChina Mainly use underground masonry plants of size 4 to 10 m3 Often use a concrete plug in the top of the dome for easy access. Some systems use the approach of removing the slurry every 6 or 12 months as fertilizer and start again.
History of biogasIndia 1897: Mumbai system gas used in lights 1907: gas used in an engine1951: KVIC national programme Developed floating drum design Plants for individual farmers of volume 7 to 35 m3 with cattle dung as feed stock Centrally planned programme with government targets
History of biogasIndia 1961: PRAD (state sector) involved Adapted Chinese dome design as “Janata” plant (4 to 10 m3) 1981: AFPRO (NGO sector) involved Adapted Chinese dome design as Deenbhandu plant (2 to 8 m3) 1981: DNES (government) gives subsidy.2009: 12 million plant built >60% success rate
History of biogasIndia 2005 ARTI won Ashden Award for a floating drum design made from HDPE water tanks Designed for urban families of volume 1 to 2 m3 with food wastes as feed stock 2007 Biotech won Ashden Award for similar system, made from glass reinforced plastics. Domestic, Institutional and Market scale
History of biogasNepal 1955: Demonstration plant in school 1968: Indian (KVIC) plant at exhibition 1975: Government programme involved Development and Consulting Services (aid programme) and Agricultural Development Bank of Nepal. 1976: Gobar Gas Company set up to continue programme as commercial operation.
History of biogasNepal Pilot programme of 95 plants used KVIC design with metal gas drums. USAID funded R&D project developed fixed dome design: cast-in-place Cattle dung used as feed stock for small farmers, using 4 to 20 m3 systems Community plants tried, but social problems prevented success.
History of biogasNepal 1986: Transferred to local management with UNDP funding and Dutch (SNV) help 1995: BSP started: central co-ordination, using many contractors (now 76) SNV and GTZ provided subsidy2009: 189,122 plants built 98% success rateCDM mechanism gives subsidy 2006: won Ashden Award
History of biogasAfrica Rwanda: Kigali Institute of Science and Technology built sewage systems for overcrowded prisons (10,000 people) Underground masonry plants: 100 m3 volume, linked to make 1,400 m3. Saves 50% of wood for cooking. Funding from Red Cross 2006: Ashden Award
History of biogasAfrica Biogas Technology West Africa Ltd. building sewage systems for hospitals, schools, colleges, etc. Underground masonry dome systems 60 to 160 m3 volume. Water recovered and used to flush toilets. Gas used for cooking.
Biogas Technologies DrumFloating drumplant (KVICdesign)Easy to see gasamountDrum can beremoved andrepaired
Biogas Technologies DrumSteel drum expensiveNeeds to be transported to siteNeeds to bepaintedCan beremoved ifloan notrepaid
Biogas Technologies DrumSeveral biogas projects in East Africahave used KVIC designBUTSteel drum canrust
Biogas Technologies DomeDCS design as used in Nepal, similarto Janata design (PRAD) in IndiaUses cast-in-place concretedomeLower cost,but highlabourrequirement
Biogas Technologies DomeUses displacement of slurry intoreservoir to collect gasConcrete dome needs to be sealed tomake it gas tightLong lifetime, ifmadecorrectly
Biogas Technologies DomeDeenbhandu design made of bricksHigh labour requirementUsesdisplacementprincipleLong life time,if madecorrectly
Biogas Technologies DomeBrick dome used for 100 m3 plantsLinked up to give 1,400 m3 plantKIST projectfor prisons inRwanda.BTWAL forhospitals,school etc. inGhana.
Kingdom Bioenergy Proposed DesignPrototype built in 1983 in NepalUses an underground concrete system Used in agricultural college. 8 more built in 2007 for large agricultural operations in Nepal
Digester used with pre-digesterBioplex system (www.bioplexltd.com) Trailer mounted – reduces handling Fixed mounting also possible 57°C fast hydrolysis meets PAS110 for compost
Advantages of Kingdom Bioenergy digesterFlexible system: can be made in arange of sizes to suit farm operation;Low cost: based on underground Asiandesigns;
Advantages of Kingdom Bioenergy digesterAdapted to UK: pre-cast concrete sections; quick to build well insulatedUse farming or food residues or both
Income/saving streams from ADGas Generate electricity (ROCs) On farm for heat (replace LPG)Compost (smell free) On farm to replace inorganic fertilizer For sale as compost (PAS 110)Gate fees for food wasteNew opportunities for biogas in UK andacross the world
Questions? www.kingdombio.comBook: Running a Biogas Programme: A Handbook Practical Action Publishers (1988) Updated version being written www.ashdenawards.org